It seems really depressing... but he did a great job on this song.
Most Helpful Guy
The song was originally written, and performed by, Nine Inch Nails. Johnny Cash only did a cover of it.
It's about regret, addiction, and all the other bad choices we make in life. Johnny Cash performed it on his final album, before he passed away.
When we look back on the choices we make, there will be regrets, and Johnny Cash had plenty of them, I'd imagine. He appropriated the song as a way of expressing some of those regrets.0